Noticed that few of my Joomla websites were still on version 2.5.11 when the current version was 2.5.19. Joomla auto-update page was misleadingly saying that Joomla was up-to-date.

To resolve the issue I had to go to Extensions > Extension Manager > Update and click Purge Cache icon.

After refreshing the administration page, Joomla finally detected version 2.5.19.

Joomla 2.5